%0 Journal Article
%A Fernando Galván, José Francisco
%A Ruiz Sancho, Jesús María
%A Scheiderer, Claus
%T Sums of squares in real rings
%D 2004
%@ 0002-9947
%U https://hdl.handle.net/20.500.14352/49910
%X Let A be an excellent ring. We show that if the real dimension of A is at least three then A has in finite Pythagoras number, and there exists a positive semidefinite element in A which is not a sum of squares in A.
%~